中国科学院数学与系统科学研究院期刊网
α-Congruences on the Sandwich Semigroups S(X, Y, θ )
Hui Sheng PEI,Hong Cun ZHAI,Yo
Acta Mathematica Sinica, Chinese Series . 2004, (2): 371 -378 .  DOI: 10.12386/A2004sxxb0047